1. Technical Field
The present invention relates to a liquid ejecting apparatus such as an ink jet printer.
2. Related Art
In general, as a printing apparatus having a detection system for detecting a jam of printing paper (also referred to as “paper jam”) transported along a predetermined direction of transport, an apparatus in which a plurality of the detection systems are arranged along a transporting route for printing paper is known (see JP-A-2000-1012). The detecting systems described above include a light-emitting portion configured to emit light and a light-receiving portion configured to receive light, respectively. Then, one of the light-emitting portion and the light-receiving portion is arranged on a back surface (that is, a surface which is not subjected to printing) of the printing paper, and the other one of the light-emitting portion and the light-receiving portion is arranged on the side of a front surface (that is, a surface which is subjected to printing) of the printing paper.
When the printing paper is transported, time counting is started when a leading end of the printing paper is detected by a first detecting system from the plurality of detecting systems, which is located on the upstream side in the direction of transport. Then, when the leading end of the printing paper cannot be detected by the second detecting system located on the downstream side in the direction of transport even though elapsed time from when the leading edge of the printing paper is detected by the first detecting system exceeds a time reference value set on the basis of a transporting speed of the printing paper, it is determined that the paper jam occurs.
For reference, a method of detecting transport failures such as the paper jam using the plurality of the detecting systems arranged along the direction of transport is also applicable in liquid ejecting apparatus having a liquid ejecting head configured to eject liquid such as ink onto a target such as the printing paper (for example, an ink jet printer).
Incidentally, the liquid ejecting apparatus is generally provided with a supporting unit configured to support a target and a carriage as a moving body which moves in a predetermined scanning direction in a movable area set on the opposite side of the supporting with the target interposed therebetween, and the liquid ejecting head is provided on the carriage. In such a liquid ejecting apparatus, a portion of the target opposing the movable area (hereinafter, referred to also as a “supported portion”) is supported by the supporting unit, and the supported portion is configured not to come into contact with the carriage or the liquid ejecting head mounted on the carriage.
However, when the transport failure of the target or the like occurs, there is a probability that the target cannot be adequately transported along the direction of transport, and at least part of the supported portion of the target may be separated from the supporting unit toward the carriage, that is, at least part of the supported portion is separated upward from the supporting unit. In such a case, there is a probability that the target comes into contact with the carriage moving in the scanning direction. When the movement of the carriage is continued without detecting such a contact, the target may become damaged due to the movement of the carriage in a state of being kept in contact with the target. Accordingly, when at least part of the supported portion of the target is separated from the supporting unit and the target and the carriage come into contact with each other, the contact is needed to be detected in an early stage.
When detecting the fact that at least part of the supported portion of the target is separated from the supporting unit using the method described in JP-A-2000-1012, a problem as shown below may occur. In other words, with the method described above, the respective detecting systems are arranged along the direction of transport of the target. In addition, the transport failure of the target is not detected unless time of a certain extent is elapsed since the detection of the leading end of the target by the first detecting system, the transport failure of the target is not detected. Therefore, there is a probability that the carriage moves in a state of being in contact with the target and hence the target becomes damaged or the degree of the damage is increased during a period from when the transport failure actually occurs until the transport failure is detected. The term “damage” used here includes unnecessary breaks of the target, or unnecessary folds of the target.
Also, separating of at least part of the supported portion of the target from the supporting unit may occur at the time other than the transport failure of the target represented by, so-called, the paper jam. For example, when the target is formed of a porous material having a liquid absorbing property in which pulp fibers (mainly composed of cellulose) made from wood constitute a mesh structure, the target absorbs ink solvent (organic solvent such as water content or alcohol) of adhered ink, and hence is swelled. Consequently, a cockling phenomenon that the target is deformed into a wavy form occurs, and at least part of the supported portion of the target may be separated from the supporting unit. In this case, separating of at least part of the supported portion of the target from the supporting unit does not cause any problem in transport of the target and hence cannot be detected with the method descried in JP-A-2000-1012.
The liquid ejecting apparatus is not limited to the type in which the liquid ejecting head is mounted on the moving body. For example, in the liquid ejecting apparatus of a type in which the liquid ejecting head is not mounted on the moving body, when the contact between the moving body and the target cannot be detected, the target may be subjected to a damage or increase in degree of the damage due to the movement of the movable member in a state in which the contact with the target is maintained in the same manner as the case of the liquid ejecting apparatus of the type in which the liquid ejecting head is mounted on the moving body.